Driving the guns to Oregon is more a matter of federal law than of California's.
If you are in legal possession of the guns, federal law permits you to carry them across state lines without jeopardy, to any location where the guns will be legally possessed.
However, the question of whether or not you will be in legal possession of the guns is something which only an attorney can answer.
If your family has access to a California attorney, I suggest that you pay for a short consultation.
(If your father had died, and had left you the guns in his will, I believe that you'd be home free: The guns would become legally your possessions upon his death.)